1. Field of the Invention
The present invention generally relates portable lighting apparatus and, more particularly, to optical, mechanical, and electrical features for the design, utility, and performance of portable task lighting and flash light apparatus using very small light emitting devices.
2. Description of the Prior Art
Lighting devices can be grouped into two basic applications: illumination devices and signaling devices. Illumination devices enable one to see into darkened areas. Signaling devices are designed to be seen, to convey information, in both darkened and well-lit areas. Widely available varieties of portable lighting apparatus, which may combine both the illumination type and the signaling type, employ a variety of lighting technologies in products such as task lamps and flashlights. Each new development in technology is followed by products that attempt to take advantage of the technology to improve performance or provide a lower cost product. For example, incandescent bulb technology in small and/or portable lighting products is being challenged by compact fluorescent lamp (CFL) bulbs, often in association with electronic ballast circuits. Other types of incandescent bulbs such as halogen lamps have become standard in a number of ordinary applications. High intensity discharge (HID) and other arc lighting technologies are finding ready markets in automotive and high brightness flood lighting, spot lighting, and signaling applications.
More recently, solid state or semiconductor devices such as light emitting diodes are finding use as compact and efficient light sources in a wide variety of applications. These applications include high intensity personal lighting, traffic and other types of signal lighting, automotive tail lamps, bicycle lighting, task lighting, flashlights, etc., to name a few examples. This technology is relatively new, however, and conventional products heretofore have suffered from a number of deficiencies. For example, current products utilizing light emitting diodes as light sources tend to be highly specialized and suited to only a single use, thus limiting their versatility as lighting devices or instruments for more ordinary uses. Further, such specialized devices tend to be expensive because of the relatively low production volumes associated with specialized applications.
Moreover, there exist certain lighting applications for which conventional light sources are unsatisfactory because of limitations in brightness, operating life, durability, power requirements, excessive physical size, poor energy efficiency, and the like. Newer light sources such as semiconductor light emitting diodes are very small, very durable, use relatively little power, have long lifetimes, and emit very bright light relative to the electrical power input. While some presently available products employ these semiconductor light sources, their full potential is frequently not realized. This may occur because of deficiencies in optical components and drive circuits, or interface components having particular combinations of structure and function are not available. Another factor may be that improvements in the design and configuration of multiple, small, high intensity light sources for maximum illumination efficiency and convenience of use have not been forthcoming.
An advance in the state of the art could be realized if such small, high intensity and high efficiency light emitting devices could be adapted to more general and more versatile lighting applications such as flood lighting or spot lighting. Such advances could occur if improvements in the components, circuits, and product architecture are developed and provided.
For example, in the field of lighting devices used by security personnel, there is a need for high intensity illumination in a battery powered, hand-held instrument that is very rugged, efficient in the use of power, and that provides a beam of light designed to illuminate dark regions of or indistinct objects within an area being patrolled or investigated. Many circumstances require a bright, well-shaped flood light beam for illuminating relatively large areas. Other situations require a more directed beam of light, to spotlight particular areas or objects. Ideally, both modes of illumination would be combined in a single instrument.